Interpretive Summary: Asparagus grown in the Pacific Northwest is normally tilled early in the spring before hand harvest begins from early April to late June. Then asparagus is tilled again after harvest, before allowing the crop to regrow and replenish reserves for the following year. Tillage has several advantages, such as removing dead fern and weeds, and incorporating preemergence-applied herbicides. However, tillage also has numerous disadvantages, such as greater soil erosion, greater water loss from soil, injury to asparagus crowns near the surface, delaying asparagus emergence and growth, and placing asparagus seed in a favorable position to become a weed in the asparagus crop. In this study, herbicides replaced tillage in the spring and at layby. The previous years dead fern was mowed off in the spring and left on the soil surface. Asparagus yield in no-till plots was equal to or better than asparagus yield in conventionally-tilled plots. Weed control with herbicides was similar among the different tillage levels. These results demonstrated that asparagus can be grown successfully under no-till in the Pacific Northwest while maintaining good weed control and high yield.

Technical Abstract:
Without herbicides, horseweed and kochia populations increased in no-till asparagus production over a 3-yr period, compared to asparagus that was rototilled either once in the spring or once in the spring and again at layby. Without herbicides, hairy nightshade populations increased most when asparagus was rototilled both in the spring and at layby. Volunteer asparagus was controlled best when herbicides and tillage were combined in the spring and again at layby. Common groundsel was controlled without herbicides by rototilling both in the spring and at layby. Diuron at 1.4 kg/ha plus prodiamine at 1.4 kg/ha or metribuzin at 0.9 plus norflurazon at 2 kg/ha controlled all weeds well under all three tillage levels when split-applied in the spring and at layby. Tillage level had no effect on total asparagus spear number or weight if tillage was performed in mid March before asparagus emergence.